Add driver for National Semiconductor LM73 temperature sensor

This driver is based on the driver for the LM75.

Signed-off-by: Larry Johnson <lrj@acm.org>
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index cebb2ba..32e3f44 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -34,6 +34,7 @@
 COBJS-y += ds1621.o
 COBJS-y += ds1722.o
 COBJS-y += ds1775.o
+COBJS-y += lm73.o
 COBJS-y += lm75.o
 COBJS-y += lm81.o